Source code menghitung luas bangun datar

#include <iostream.h>

#define phi 3.14

main ()

{

                float p,l,s,a,t,r,hasil;

                char menu,n;

                Ulang:

                cout<<"Menghitung Luas Bangun"<<endl;

                cout<<""<<endl;

                cout<<"Di Buat Oleh :"<<endl;

                cout<<"K******* (171080***)"<<endl;

                cout<<""<<endl;              

                cout<<"Menu :\nA. Luas Persegi Panjang\nB. Luas Persegi\n";

                cout<<"C. Luas Segitiga\nD. Luas Lingkaran\nE. Keluar\n";

                cout<<""<<endl;

                cout<<"Pilih menu(A,B,C,D,E) = ";

                cin>> menu;

switch(menu){

                case 'A':

                case 'a':

                                cout<<"Menghitung Luas Persegi Panjang\n";

                                cout<<"Masukkan Panjang (P) :";

                                cin>>p;

                                cout<<"Masukkan Lebar (L) :";

                                cin>>l;

                                hasil = p*l;

                                cout <<"Luas Persegi Panjang adalah = " << hasil << endl;

                                cout<<endl;

                cout<<" Hitung Ulang (Y/N) : ";

                cin>>n;

                cout<<"\n\n";

                if (n=='y'||n=='Y')           

                                goto Ulang;

                                break;

                case 'B':

                case 'b':

                                cout<<"Menghitung Luas Persegi\n";

                                cout<<"Masukkan Sisi(S) :";

                                cin>>s;

                                hasil = s*s;

                                cout <<"Luas Persegi adalah = " << hasil << endl;

                                cout<<endl;

                cout<<" Hitung Ulang (Y/N) : ";

                cin>>n;

                cout<<"\n\n";

                if (n=='y'||n=='Y')           

                                goto Ulang;

                                break;

                case 'C':

                case 'c':

                                cout<<"Menghitung Luas Segitiga\n";

                                cout<<"Masukkan Alas(a) : ";

                                cin>>a;

                                cout<<"Masukkan Tinggi(t) : ";

                                cin>>t;

                                hasil = (a*t)*0.5;

                                cout <<"Luas Segitiga adalah = " << hasil << endl;

                                cout<<endl;

                cout<<" Hitung Ulang (Y/N) : ";

                cin>>n;

                cout<<"\n\n";

                if (n=='y'||n=='Y')           

                                goto Ulang;

                                break;

                case 'D':

                case 'd':

                                cout<<"Menghitung Luas Lingkaran\n";

                                cout<<"Masukkan Jari Jari(r) : ";

                                cin>>r;

                                hasil = phi*(r*r);

                                cout <<"Luas Lingkaran adalah = " << hasil << endl;

                                cout<<endl;

                cout<<" Hitung Ulang (Y/N) : ";

                cin>>n;

                cout<<"\n\n";

                if (n=='y'||n=='Y')           

                                goto Ulang;

                                break;

                case 'E':

                case 'e':

                                cout<<"Anda Yakin Ingin Keluar (Y/T)?\n";

                                cin>>n;

                                if (n=='t'||n=='T')            

                                goto Ulang;

                                break;

                }}